Wheel suspension Description 5 The invention relates to a wheel suspension according to the precharacterising clause of Claim 1. The wheel suspension of a motor vehicle is of crucial importance in particular with regard to comfort and also 10 safety. Therefore, interfering effects acting on the wheel suspension must be optimally compensated for. During cornering, due to the centrifugal force on the vehicle body, an inclination arises, which is referred to 15 as roll. This results in the vehicle body moving in the direction of the outside of the corner. In the process, the weight of the vehicle is transferred predominantly to the wheels of the motor vehicle which are situated on the outside of the corner, while the vehicle wheels situated on 20 the inside of the corner are relieved accordingly. The inclination of the wheel relative to the road surface which arises in particular on the outer vehicle wheel on the corner and is referred to as camber may lead to premature wear on account of the extremely high loading of the 25 vehicle tyres. In addition, it has been found that a lower lateral force potential is available owing to the camber of the vehicle wheel. The camber arising on the vehicle wheel consequently leads to a change in the tyre contact area, so that the vehicle wheel loses valuable adhesion to the 30 ground. Twin-control-arm axles known hitherto compensate for this camber by specifically influencing the wheel position by 2 producing a negative camber, which is directed in the opposite direction and which can be achieved by different lengths and/or orientations of the transverse control arms. However, this leads to disadvantages during straight-ahead 5 travel of the motor vehicle, namely when individual vehicle wheels undergo an inward deflection on one side, as can happen, for example, when travelling over unevennesses of the ground. 10 To reduce the roll of the vehicle body during cornering, it is generally known to couple to each other the vehicle wheels located opposite each other when viewed in the transverse direction of the motor vehicle by means of a stabiliser. The stabiliser thus establishes a connection 15 between the inward-deflected outer vehicle wheel on the corner and the outward-deflected inner vehicle wheel on the corner, with the aim of reducing the inward-deflection movements. The stabilisers employed are of mechanical design consisting, for example, of a bar bent in a U-shape, 20 the open ends of this U-shaped stabiliser being coupled to the vehicle wheels. This stabiliser consequently acts as a torsion bar and produces a torque directed opposite the deflection of the vehicle wheels. 25 Furthermore, both active stabilisers, equipped with an actuator, and switchable stabilisers are known. The switchable designs in particular are employed in off-road vehicles and have a switching unit which enables separation of the stabiliser halves. This separation is required for 30 optimal handling of the vehicle on uneven terrain. A switchable stabiliser for a motor vehicle, which besides having the possibility of uncoupling the stabiliser halves 3 additionally exhibits damping, is known, for example, from DE 10 2005 013 769 Al. The stabiliser ends are not usually attached directly to 5 the vehicle wheel, but via a coupling member, which is generally a pendulum support. Switchable versions are also known for such pendulum supports. In this regard, reference is made merely by way of example to DE 10 2004 025 807 Al. 10 A special wheel suspension for a motor vehicle is known from US 6,929,271 B2. This wheel suspension has stabilisers for correcting wheel positions, such as the wheel camber, with provision being made both for a connection of two wheels located opposite each other, i.e. the wheels of the 15 two sides of the vehicle, and for a coupling of front wheels to rear wheels. Double-acting piston-cylinder units, which are integrated in the stabiliser of the motor vehicle and which bring about a compensation for undesired wheel movements, for example, during cornering, are present in 20 this solution. The wheel suspension known from US 6,929,271 B2 has a transverse control arm, which is coupled in an articulated manner to a wheel carrier carrying a vehicle wheel. 25 The common feature of these known solutions is that the forces acting on the vehicle wheels and the displacements, which result therefrom, of the vehicle wheels in the form of a camber arising thereon can be compensated for by coupling a plurality of vehicle wheels to one another. 30 However, hitherto the results of the camber compensation have been unsatisfactory. In addition, it has been found that besides the camber on the vehicle wheel in particular during cornering a not inconsiderable change in track 4 occurs, which adversely affects the handling of the motor vehicle. Hitherto, there have been scarcely any known solutions worth pursuing to compensate for this additional effect. 5 The object on which the invention is based is to provide a wheel suspension for a motor vehicle which enables both correction of the camber and maintaining of the track and which can be employed as far as possible for various wheel 10 suspension designs. A wheel suspension of a motor vehicle having a wheel carrier which carries a vehicle wheel and is of two-part design, the first part of which is connected to a second 15 part in an articulated manner, at least one compensating means being present for the connection of the first part of the wheel carrier to the second part of the wheel carrier, has been developed in that the vehicle wheel has an operative connection, formed by a stabiliser, to a vehicle 20 wheel present on the opposite side of the vehicle when viewed in the transverse direction of the motor vehicle, and the stabiliser is connected to the compensating means in an articulated manner. 25 The disadvantage of the wheel suspensions known from the prior art having a passive kinematic adjustment is that, in particular during cornering, the wheel contact point is displaced in the direction of the motor vehicle. The reduction of the track which thus results leads to 30 increased roll of the vehicle body. This change in track of the vehicle wheel, which is found to be disadvantageous, and its camber can be compensated for almost completely with a solution according to the invention. The vehicle 5 wheel in this case has an optimal wheel contact area also during cornering. This results in an increase of the static friction between the vehicle wheel and the ground, which is accompanied by a considerable increase in safety and not 5 least also of the riding comfort for the motor vehicle. The improvement over conventional wheel suspension systems lies in the stabiliser which is attached to a divided wheel carrier. The two-part design of the wheel carrier according 10 to the invention enables a relative movement of the individual parts of the wheel carrier to one another. The positive camber arising on the vehicle wheel during cornering, that is to say the setting of the vehicle wheel at an angle to the road surface, is converted by this 15 solution into an opposite, i.e. negative, camber, so that the vehicle wheel has an almost vertical orientation also during cornering. In accordance with a first embodiment variant of the 20 invention, it is proposed that the wheel suspension has a lower compensating means close to the ground and an upper compensating means at a different height from the lower compensating means. According to the invention, the compensating means serve in each case for coupling the 25 parts of the wheel carrier to one another and enabling their relative movement. Furthermore, the compensating means may serve for connecting further elements essential for the wheel suspension, such as, for example, for attaching transverse control arms. In the present case, it 30 is particularly advantageous for the stabiliser to be attached to the upper compensating means. In this way, the lever ratios and thus the influence on the vehicle wheel can be designed to be particularly favourable.
6 Besides a conventional stabiliser which, as has already been stated at the outset, can consist, for example, of a bar-shaped element, stabilisers which include active 5 elements may also be employed in the case of the solution according to the invention. Accordingly, a development of the invention is to provide an active stabiliser for use in a wheel suspension according to the invention. By means of the active stabiliser, significantly greater forces can be 10 produced compared with conventional, mechanical stabilisers, so that the camber adjustment of the vehicle wheel can be increased. Furthermore, the active stabilisers allow a geometrically advantageous connection of the various components. 15 The stabiliser connected to the compensating means need not necessarily be directly mounted on the compensating means. Rather, in the case of a wheel suspension according to the invention, an indirect fastening of the stabiliser can also 20 advantageously be implemented. In this case, the connection between the stabiliser and the compensating means can consist of a coupling member, it being possible to use a pendulum support as the coupling member. With this solution, the kinematic conditions within the context of 25 the present wheel suspension can be significantly improved. A further configuration of the invention is for the coupling member to be an active coupling member. With active coupling members, the properties of the wheel 30 suspension can likewise be optimised as has already been explained above in connection with the active stabilisers.
7 The compensating means employed may advantageously be rotary links in particular, where rotary links are understood as in each case triangular links having three joints or four-point links having four joints. The rotary 5 links or compensating means constitute elements inside the wheel suspension which enable movement transmission. The joints employed may be spherical joints, revolute joints or joints with elastic properties. Joints with 10 elastic properties are also known as elastomer bearings. The present invention will be explained in more detail below on the basis of the drawings attached. The exemplary embodiments shown do not represent any limitation to the 15 variants shown, but are used merely to explain some principles of wheel suspensions according to the invention. Identical or similar components are designated by the same reference numbers. To make it possible to illustrate the mode of operation according to the invention, the figures 20 show only greatly simplified schematic illustrations, in which the components that are not essential for the invention, are omitted. However, this does not mean that such components are not present in a wheel suspension according to the invention. 25 In the drawings: Figure 1 shows a schematically simplified illustration of a first embodiment variant of a wheel suspension 30 according to the invention in a non-deflected position of the vehicle wheel, Figure 2 shows the wheel suspension according to Figure 1 deflected under the influence of a lateral force, 8 Figure 3 shows a further embodiment, in a simplified schematic illustration, for a wheel suspension according to the invention in a non-deflected position of the vehicle wheel, 5 Figure 4 shows a third variant of a wheel suspension according to the invention in a non-deflected, simplified schematic illustration, and Figure 5 shows a schematic illustration in simplified form 10 for a fourth embodiment of a wheel suspension according to the invention. The wheel suspensions according to the present invention which are shown in Figures 1 and 2 represent a simplified 15 design corresponding to a first variant, with Figure 1 showing a non-deflected wheel suspension and Figure 2 showing the wheel suspension from Figure 1 deflected under the influence of the lateral force Fs. This wheel suspension has a vehicle wheel 1, which is fastened to, 20 i.e. rotatably mounted on, a wheel carrier designated as a whole by 2. The wheel carrier 2 consists of a first part 3 and a second part 4. The two parts 3 and 4 of the wheel carrier 2 are coupled to one another in an articulated manner. They have a direct connection at a joint 15 and an 25 indirect connection via a compensating means 5, to which the first part 3 of the wheel carrier 2 is fastened at the joint 5a and the second part 4 of the wheel carrier 2 is fastened at the joint 5c. The second part 4 of the wheel carrier 2 further has two joints 13 and 14 which serve for 30 the attachment of in each case one transverse control arm 9 and 10, respectively. The transverse control arms 9, 10 have, in a manner known per se, a connection to the motor vehicle and can be articulated, for example, on the vehicle 9 body 11. A shock absorber 12 for reducing the movements introduced via the wheel suspension is further present on the transverse control arm 9. Overall, in the case of the wheel suspension in Figures 1 and 2, the fundamental 5 principle involved is that which is known as a twin control-arm wheel suspension. Situated between the first part 3 and the second part 4 of the wheel carrier 2 is furthermore a spring 16 which causes the two parts 3 and 4 of the wheel carrier 2 to return to their neutral starting 10 position. A coupling member 8 is further attached at the joint 5b on the upper compensating means 5 of the embodiment variant of a wheel suspension according to the invention shown in Figure 1. The coupling member 8 illustrated is a pendulum support which serves for the 15 indirect connection of the stabiliser 7 to the wheel suspension. The stabiliser 7 is, in a manner known per se, for its part connected to the vehicle body 11 via a stabiliser bearing 18. In the case of the non-deflected variant of the wheel suspension in Figure 1, it should be 20 noted that the vehicle wheel 1 is oriented in an approximately vertical position on the vehicle. A negative camber provided by design in this neutral position does not have to be present in the case of this solution according to the invention, so that the wheel is actually vertically 25 oriented. The parts 3 and 4 of the wheel carrier 2 also have in this case an approximately parallel arrangement to one another. Such a position of the components relative to one another would arise, for example, during straight-ahead travel of the motor vehicle. 30 In contrast to this, in the identically constructed embodiment variant in Figure 2, the same wheel suspension is shown deflected. Under the influence of a lateral force 10 Fs, such as that which acts on the vehicle wheel 1, for example, during cornering, the vehicle wheel 1 tends to depart from its vertical position and assume a "positive" camber. This "positive" camber is, however, optimally 5 counteracted by the wheel suspension according to the invention. As can be seen from Figure 2, a twisting, i.e. a torsion, is produced in the stabiliser 7 owing to the inward deflection of the vehicle wheel 1. This torsion in turn results in a force which forces the outer wheel on the 10 corner back into its neutral design position. This force is transmitted to the compensating means 5 via the pendulum support 8. For optimal design of the system, it is advantageous if the joint 5b on the compensating means is an elastomer bearing. Owing to the force introduced via the 15 stabiliser, the vehicle wheel 1 is brought into a "negative camber". That is to say, it is moved oppositely to the positive camber arising on account of the cornering. The vehicle wheel 1 thus has an almost vertical orientation also during cornering, while the movements are taken up 20 inside the wheel carrier 2. The parts 3 and 4 of the wheel carrier 2 pivot here about the joint 15 in the lower part of the wheel carrier 2. The force action applied to the compensating means 5 via the stabiliser 7 and the pendulum support 8 results in a rotational movement of the 25 compensating means 5 about the joint 5c, so that the joint 5b is moved in the direction of the road surface, i.e. downwards in the illustration of Figure 2. The movement corresponds roughly to a circular path. Owing to the influence of the wheel suspension thereby arising on the 30 upper articulation point 5a of the compensating means 5, the first part 3 of the wheel carrier 2 is pivoted about the articulation point 15 relative to the second part 4 of 11 the wheel carrier 2. Thus, a movement of the vehicle wheel 1 in the direction of a negative camber can be achieved. The embodiment variant of a solution according to the 5 invention for a wheel suspension shown in Figure 3 represents a non-deflected system. In contrast to the wheel suspension already explained above, this wheel suspension has an upper compensating means 5 configured as a four point link and, at a different height therefrom, a lower 10 compensating means 6 configured as a three-point link. The vehicle wheel 1 is again fastened to the first part 3 of the wheel carrier 2. The first part 3 of the wheel carrier 2 has a connection to the first compensating means 5 at the articulation point 5a. The second part 4 of the wheel 15 carrier 2 is attached to the four-point link 5 at the articulation point 5c. The joint 5b, which is also formed as an elastomer bearing in the present case, is connected to the pendulum support 8. Furthermore, a further pendulum support 17 is present as a coupling member in the case of 20 this wheel suspension. This pendulum support 17 is attached at one end to the joint 5d of the upper four-point link and is fastened at the other end at the joint 6b of the lower compensating means 6 designed as a three-point link. The joint 6a of the lower compensating means 6 serves for the 25 connection of the second part 4 of the wheel carrier 2 in its lower region and provides a connection to the lower transverse control arm 10. The joint 6a thus also corresponds in its function to the joint 14 of the embodiment variant in Figures 1 and 2. The third joint of 30 the compensating means 6 designed as a three-point link is the joint 6c. This joint serves for the connection of the first part 3 of the wheel carrier 2, this connection being present in the lower part of the wheel carrier part 3. The 12 upper transverse control arm 9 is connected to the second part 4 of the wheel carrier 2 via the joint 13. The variant of a wheel suspension according to the invention illustrated in Figure 3 represents a structurally more 5 complex system compared with the wheel suspension explained in conjunction with Figures 1 and 2, but has the advantage that it enables further optimisation both of the camber behaviour of the vehicle wheel and a reduction of the change in track of the vehicle wheel 1 to be achieved. With 10 a variant of this type, the change in track can be reduced almost to a value of "zero", even if the vehicle wheel is steered through a corner at high speed. A further, very special embodiment of a wheel suspension 15 according to the invention is shown in Figure 4. The fundamental structure of this wheel suspension corresponds to the system already explained in conjunction with Figures 1 and 2. In contrast to this system, however, the stabiliser 7 has an actuator 19. With an embodiment of this 20 type, too, the change in track of the vehicle wheel 1 can be reduced to a value close to zero, which was not possible in the case of wheel suspensions known hitherto. Compared with the wheel suspension described in conjunction with Figures 1 and 2, in the case of the variant shown in Figure 25 4 an even greater negative camber can be specifically established, since the forces which can be introduced are higher in the case of an active stabiliser than a conventional, mechanical stabiliser. A further advantage of this embodiment variant in Figure 4 is that it requires 30 fewer components than the mechanical design of a wheel suspension. Thus, for example, a single upper compensating means 5 can suffice. Consequently, no further compensating means, i.e. no lower compensating means 6, is required. The 13 compensating functions of the lower compensating means 6 according to Figure 3 are taken over in the present exemplary embodiment of Figure 4 by the active stabiliser 7. 5 Another embodiment of the invention is illustrated in Figure 5. Here, too, a wheel suspension as already explained in conjunction with Figures 1 and 2 may be employed. The fundamental structure is identical to this 10 system. The difference in the case of the embodiment variant in Figure 5 consists in that here an active pendulum support 20 is present between the stabiliser 7 and the upper compensating means 5. The compensating means 5 is in this case configured as a triangular link. In the case 15 of the embodiment in Figure 5, too, a very simple mechanism may be employed and nevertheless a lower compensating means 6 can be dispensed with. An upper compensating means 5, which in the present case has again been configured as a triangular link, is sufficient for the optimal adjustment 20 of the vehicle wheel 1. A combination of the wheel suspension illustrated in Figure 3 with active elements (stabiliser and/or pendulum support) is, of course, also possible. The corresponding components 25 have to be adapted, at reasonable expense, in order to achieve an optimal reduction of the change in track and an optimised camber on the vehicle wheel 1. The principles of the invention described in conjunction 30 with the figures are, of course, not restricted to the twin-control-arm axles described here, but may also be used in other, structurally different, wheel suspension systems.
14 List of reference symbols 1. vehicle wheel 2. wheel carrier 5 3. first part of the wheel carrier 4. second part of the wheel carrier 5. compensating means 6. compensating means 7. stabiliser 10 8. coupling member 9. transverse control arm 10. transverse control arm 11. vehicle body 12. shock absorber 15 13. joint 14. joint 15. joint 16. spring 17. coupling member 20 18. stabiliser bearing 19. actuator 20. active pendulum support a, b, c, d joints